Delilah Prestwick

Major spoiler alert in this article for Catalyst. If you do not want this book spoiled, do not continue reading.

Delilah Prestwick is the mother of Tom Raines, main protagonist throughout the series and trainee for the Intrasolar Forces. She is mentioned multiple times throughout the series, but her past and almost everything else we know of her is revealed in Catalyst, the third book in the series.

History
Not much is known about Delilah's life before Tom, but we do know based on confirmation from both Dalton Prestwick and Tom's father, Neil, that after having Tom, she began having extreme spurts of violent actions, after which Neil later said "she didn't even understand what she'd done." One extremely violent episode saw her leaving with Tom and setting fire to a house. It was this incident in particular that caused Neil to realize that Delilah was a threat to both him and Tom, so he was glad when Joseph Vengerov offered to try an "experimental treatment" on her brain that he only very later learned was the implementation of a neural processor, so he signed both him and Delilah away for full medical custody, not knowing what he was really doing. Because only a young brain could handle a processor, Delilah suffered severe seizures like many of the other test subjects and Vengerov decided to take out various parts of her brain to see how much he had to take out while still maintaining some basic functionality. She lost the entire frontal lobe of her brain, essentially everything that made her her, and the part that handles speech, but the neural processor took care of that. (This caused Neil to also take Tom back before he could be experimented on.) After experimentation, she was given to Dalton Prestwick, who reprogrammed her as essentially a slave to him, taking commands from him without question, which was only possible because her lack of a frontal lobe prevented her from questioning anything.

Insignia & Vortex
Delilah does not make any direct appearance in either of these books, although we do get recollections from Tom of encounters from his mother post-processor, in which Tom just assumes she does not care about him because of her nature, but where we later learn is only because she lost her frontal lobe. Under the census device, Tom also recalls memories of his mother being very kind to him, which confuses him because the only memories he remembers outside of the census device are of a very different mother.

Catalyst
After the damage caused by the meteor Cruithne, Tom assumes his father either dead or missing, and either way he does not know where to find him and he is obligated to go with one of his parents over break, so he goes to his mother's, with hopes that he will just fend for his own and not have to talk to her beyond checking into her apartment. But when he arrives, he notices her blinking pattern: exactly fifteen seconds between each one, one of the effects of a neural processor. Up until that point, Tom had not known of his mother's neural processor, so this is an enormous shock to him. He immediately assumes that this was Dalton's fault, so he tackles him and demands answers, at which point Dalton tells him the whole story of his mother getting her neural processor, and how Dalton took her afterward. This enrages Tom, but he cannot do much about it except force-feed Dalton Austere-Grade neural processors.

Later in the story, after Vengerov is defeated, Tom goes to Dalton's apartment and uses his own neural processor to turn off Delilah's, killing her but freeing her because she no longer has to be a machine. Dalton comes in at this point and sees what Tom has done, enraged. Tom realizes at this point that Dalton never loved Delilah, just her neural processor. After a brief and heated conversation about Dalton's rejection in society as a Dominion Agra executive, Tom takes Dalton to a police station and tells him to confess. This is the last time both Dalton and Delilah make direct appearances in the series.

Later, Tom and Yaolan meet Tom's father to restore his memories of Tom after Vengerov erased all of them after Neil was given an Austere-Grade processor. Tom tells his father that he knows about his mother, and about how he shut off her neural processor. Neil forgives him, saying it was the best thing for her, and then tells Tom about how Vengerov had approached him. Dalton had never told Tom about it, he had just said that Neil wanted Delilah off her hands, but Neil tells him the truth about his hopes that Vengerov would fix Delilah. Tom realizes then that his dad was never as bad as Dalton made him out to be.